PPAPI/NaCl: Speculative implementation for ipc_channel_nacl.cc

ipc/ipc_channel_nacl.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ipc/ipc_channel_nacl.h"
 
+#include <errno.h>
+#include <stddef.h>
+#include <sys/nacl_imc_api.h>
+#include <sys/nacl_syscalls.h>
+#include <sys/types.h>
+
+#include <algorithm>
+
+#include "base/bind.h"
 #include "base/file_util.h"
 #include "base/logging.h"
-
-// This file is currently a stub to get us linking.
-// TODO(brettw) implement this.
+#include "base/message_loop_proxy.h"
+#include "base/process_util.h"
+#include "base/synchronization/lock.h"
+#include "base/task_runner_util.h"
+#include "base/threading/simple_thread.h"
+#include "ipc/file_descriptor_set_posix.h"
+#include "ipc/ipc_logging.h"
 
 namespace IPC {
+namespace {
+
+scoped_ptr<std::vector<char> > ReadDataOnReaderThread(int pipe) {
+  DCHECK(pipe >= 0);
+
+  if (pipe < 0)
+    return scoped_ptr<std::vector<char> >();
+
+  scoped_ptr<std::vector<char> > buffer(
+      new std::vector<char>(Channel::kReadBufferSize));
+  struct NaClImcMsgHdr msg = {0};
+  struct NaClImcMsgIoVec iov = {&buffer->at(0), buffer->size()};
+  msg.iov = &iov;
+  msg.iov_length = 1;
+
+  int bytes_read = imc_recvmsg(pipe, &msg, 0);
+
+  if (bytes_read <= 0) {
+    // NaClIPCAdapter::BlockingReceive returns -1 when the pipe closes (either
+    // due to error or for regular shutdown).
+    return scoped_ptr<std::vector<char> >();
+  }
+  DCHECK(bytes_read);
+  buffer->resize(bytes_read);
+  return buffer.Pass();
+}
+
+}  // namespace
+
+class Channel::ChannelImpl::ReaderThreadRunner
+    : public base::DelegateSimpleThread::Delegate {
+ public:
+  // |pipe|: A file descriptor from which we will read using imc_recvmsg.
+  // |data_read_callback|: A callback we invoke (on the main thread) when we
+  //                       have read data. The callback is passed a buffer of
+  //                       data that was read.
+  // |failure_callback|: A callback we invoke when we have a failure reading
+  //                     from |pipe|.
+  // |main_message_loop|: A proxy for the main thread, where we will invoke the
+  //                      above callbacks.
+  ReaderThreadRunner(
+      int pipe,
+      base::Callback<void (scoped_ptr<std::vector<char> >)> data_read_callback,
+      base::Callback<void ()> failure_callback,
+      base::MessageLoopProxy* main_message_loop);
+
+  // DelegateSimpleThread implementation. Reads data from the pipe in a loop
+  // until either we are told to quit or a read fails.
+  virtual void Run() OVERRIDE;
+
+ private:
+  int pipe_;
+  base::Callback<void (scoped_ptr<std::vector<char> >)> data_read_callback_;
+  base::Callback<void ()> failure_callback_;
+  base::MessageLoopProxy* main_message_loop_;
+
+  DISALLOW_COPY_AND_ASSIGN(ReaderThreadRunner);
+};
+
+Channel::ChannelImpl::ReaderThreadRunner::ReaderThreadRunner(
+    int pipe,
+    base::Callback<void (scoped_ptr<std::vector<char> >)> data_read_callback,
+    base::Callback<void ()> failure_callback,
+    base::MessageLoopProxy* main_message_loop)
+    : pipe_(pipe),
+      data_read_callback_(data_read_callback),
+      failure_callback_(failure_callback),
+      main_message_loop_(main_message_loop) {
+}
+
+void Channel::ChannelImpl::ReaderThreadRunner::Run() {
+  while (true) {
+    scoped_ptr<std::vector<char> > buffer(ReadDataOnReaderThread(pipe_));
+    if (buffer.get()) {
+      main_message_loop_->PostTask(FROM_HERE,
+          base::Bind(data_read_callback_, base::Passed(buffer.Pass())));
+    } else {
+      main_message_loop_->PostTask(FROM_HERE, failure_callback_);
+      // Because the read failed, we know we're going to quit. Don't bother
+      // trying to read again.
+      return;
+    }
+  }
+}
 
 Channel::ChannelImpl::ChannelImpl(const IPC::ChannelHandle& channel_handle,
-                         Mode mode,
-                         Listener* listener)
-    : ChannelReader(listener) {
+                                  Mode mode,
+                                  Listener* listener)
+    : ChannelReader(listener),
+      mode_(mode),
+      waiting_connect_(true),
+      pipe_(-1),
+      pipe_name_(channel_handle.name),
+      weak_ptr_factory_(ALLOW_THIS_IN_INITIALIZER_LIST(this)) {
+  if (!CreatePipe(channel_handle)) {
+    // The pipe may have been closed already.
+    const char *modestr = (mode_ & MODE_SERVER_FLAG) ? "server" : "client";
+    LOG(WARNING) << "Unable to create pipe named \"" << channel_handle.name
+                 << "\" in " << modestr << " mode";
+  }
+  reader_thread_runner_.reset(
+      new ReaderThreadRunner(
+          pipe_,
+          base::Bind(&Channel::ChannelImpl::DidRecvMsg,
+                     weak_ptr_factory_.GetWeakPtr()),
+          base::Bind(&Channel::ChannelImpl::ReadDidFail,
+                     weak_ptr_factory_.GetWeakPtr()),
+          base::MessageLoopProxy::current()));
+  reader_thread_.reset(
+      new base::DelegateSimpleThread(reader_thread_runner_.get(),
+                                     "ipc_channel_nacl reader thread"));
 }
 
 Channel::ChannelImpl::~ChannelImpl() {
   Close();
 }
 
 bool Channel::ChannelImpl::Connect() {
-  NOTIMPLEMENTED();
-  return false;
+  if (pipe_ == -1) {
+    DLOG(INFO) << "Channel creation failed: " << pipe_name_;
+    return false;
+  }
+
+  reader_thread_->Start();
+  waiting_connect_ = false;
+  // If there were any messages queued before connection, send them.
+  ProcessOutgoingMessages();
 }
 
 void Channel::ChannelImpl::Close() {
-  NOTIMPLEMENTED();
+  // For now, we assume that at shutdown, the reader thread will be woken with
+  // a failure (see NaClIPCAdapter::BlockingRead and CloseChannel). Or... we
+  // might simply be killed with no chance to clean up anyway :-).
+  // If untrusted code tries to close the channel prior to shutdown, it's likely
+  // to hang.
+  // TODO(dmichael): Can we do anything smarter here to make sure the reader
+  //                 thread wakes up and quits?
+  reader_thread_->Join();
+  close(pipe_);
+  pipe_ = -1;
+  reader_thread_runner_.reset();
+  reader_thread_.reset();
+  read_queue_.clear();
+  output_queue_.clear();
 }
 
 bool Channel::ChannelImpl::Send(Message* message) {
-  NOTIMPLEMENTED();
+  DVLOG(2) << "sending message @" << message << " on channel @" << this
+           << " with type " << message->type();
+  scoped_ptr<Message> message_ptr(message);
+
+#ifdef IPC_MESSAGE_LOG_ENABLED
+  Logging::GetInstance()->OnSendMessage(message, "");
+#endif  // IPC_MESSAGE_LOG_ENABLED
+
+  output_queue_.push_back(linked_ptr<Message>(message));
+  if (!waiting_connect_)
+    return ProcessOutgoingMessages();
+
+  return true;
 }
 
-int Channel::ChannelImpl::GetClientFileDescriptor() const {
-  NOTIMPLEMENTED();
-  return -1;
+void Channel::ChannelImpl::DidRecvMsg(scoped_ptr<std::vector<char> > buffer) {
+  // Close sets the pipe to -1. It's possible we'll get a buffer sent to us from
+  // the reader thread after Close is called. If so, we ignore it.
+  if (pipe_ == -1)
+    return;
+
+  read_queue_.push_back(linked_ptr<std::vector<char> >(buffer.release()));
 }
 
-int Channel::ChannelImpl::TakeClientFileDescriptor() {
-  NOTIMPLEMENTED();
-  return -1;
+void Channel::ChannelImpl::ReadDidFail() {
+  Close();
 }
 
-bool Channel::ChannelImpl::AcceptsConnections() const {
-  NOTIMPLEMENTED();
-  return false;
+bool Channel::ChannelImpl::CreatePipe(
+    const IPC::ChannelHandle& channel_handle) {
+  DCHECK(pipe_ == -1);
+
+  // There's one possible case in NaCl:
+  // 1) It's a channel wrapping a pipe that is given to us.
+  // We don't support these:
+  // 2) It's for a named channel.
+  // 3) It's for a client that we implement ourself.
+  // 4) It's the initial IPC channel.
+
+  if (channel_handle.socket.fd == -1) {
+    NOTIMPLEMENTED();
+    return false;
+  }
+  pipe_ = channel_handle.socket.fd;
+  return true;
 }
 
-bool Channel::ChannelImpl::HasAcceptedConnection() const {
-  NOTIMPLEMENTED();
-  return false;
+bool Channel::ChannelImpl::ProcessOutgoingMessages() {
+  DCHECK(!waiting_connect_);  // Why are we trying to send messages if there's
+                              // no connection?
+  if (output_queue_.empty())
+    return true;
+
+  if (pipe_ == -1)
+    return false;
+
+  // Write out all the messages. The trusted implementation is guaranteed to not
+  // block. See NaClIPCAdapter::Send for the implementation of imc_sendmsg.
+  while (!output_queue_.empty()) {
+    linked_ptr<Message> msg = output_queue_.front();
+    output_queue_.pop_front();
+
+    struct NaClImcMsgHdr msgh = {0};
+    struct NaClImcMsgIoVec iov = {const_cast<void*>(msg->data()), msg->size()};
+    msgh.iov = &iov;
+    msgh.iov_length = 1;
+    ssize_t bytes_written = imc_sendmsg(pipe_, &msgh, 0);
+
+    if (bytes_written < 0) {
+      // The trusted side should only ever give us an error of EPIPE. We
+      // should never be interrupted, nor should we get EAGAIN.
+      DCHECK(errno == EPIPE);
+      Close();
+      PLOG(ERROR) << "pipe_ error on "
+                  << pipe_
+                  << " Currently writing message of size: "
+                  << msg->size();
+      return false;
+    }
+
+    // Message sent OK!
+    DVLOG(2) << "sent message @" << msg.get() << " with type " << msg->type()
+             << " on fd " << pipe_;
+  }
+  return true;
 }
 
-bool Channel::ChannelImpl::GetClientEuid(uid_t* client_euid) const {
-  NOTIMPLEMENTED();
-  return false;
-}
-
-void Channel::ChannelImpl::ResetToAcceptingConnectionState() {
-  NOTIMPLEMENTED();
-}
-
-Channel::ChannelImpl::ReadState
-    Channel::ChannelImpl::ReadData(char* buffer,
-                                   int buffer_len,
-                                   int* bytes_read) {
-  return Channel::ChannelImpl::ReadState();
+Channel::ChannelImpl::ReadState Channel::ChannelImpl::ReadData(
+    char* buffer,
+    int buffer_len,
+    int* bytes_read) {
+  *bytes_read = 0;
+  if (pipe_ == -1)
+    return READ_FAILED;
+  if (read_queue_.empty())
+    return READ_PENDING;
+  while (!read_queue_.empty() && *bytes_read < buffer_len) {
+    linked_ptr<std::vector<char> > vec(read_queue_.front());
+    int bytes_to_read = buffer_len - *bytes_read;
+    if (vec->size() <= bytes_to_read) {
+      // We can read and discard the entire vector.
+      std::copy(vec->begin(), vec->end(), buffer + *bytes_read);
+      *bytes_read += vec->size();
+      read_queue_.pop_front();
+    } else {
+      // Read all the bytes we can and discard them from the front of the
+      // vector. (This can be slowish, since erase has to move the back of the
+      // vector to the front, but it's hopefully a temporary hack and it keeps
+      // the code simple).
+      std::copy(vec->begin(), vec->begin() + bytes_to_read,
+                buffer + *bytes_read);
+      vec->erase(vec->begin(), vec->begin() + bytes_to_read);
+      *bytes_read += bytes_to_read;
+    }
+  }
+  return READ_SUCCEEDED;
 }
 
 bool Channel::ChannelImpl::WillDispatchInputMessage(Message* msg) {
-  return false;
+  return true;
 }
 
 bool Channel::ChannelImpl::DidEmptyInputBuffers() {
-  return false;
+  return true;
 }
 
 void Channel::ChannelImpl::HandleHelloMessage(const Message& msg) {
-}
-
-// static
-bool Channel::ChannelImpl::IsNamedServerInitialized(
-    const std::string& channel_id) {
-  return false;  //file_util::PathExists(FilePath(channel_id));
+  // The trusted side IPC::Channel should handle the "hello" handshake; we
+  // should not receive the "Hello" message.
+  NOTREACHED();
 }
 
 //------------------------------------------------------------------------------
 // Channel's methods simply call through to ChannelImpl.
 
 Channel::Channel(const IPC::ChannelHandle& channel_handle,
                  Mode mode,
                  Listener* listener)
     : channel_impl_(new ChannelImpl(channel_handle, mode, listener)) {
 }
 
 Channel::~Channel() {
   delete channel_impl_;
 }
 
 bool Channel::Connect() {
   return channel_impl_->Connect();
 }
 
 void Channel::Close() {
   channel_impl_->Close();
 }
 
 void Channel::set_listener(Listener* listener) {
   channel_impl_->set_listener(listener);
 }
 
+base::ProcessId Channel::peer_pid() const {
+  // This shouldn't actually get used in the untrusted side of the proxy, and we
+  // don't have the real pid anyway.
+  return -1;
+}
+
 bool Channel::Send(Message* message) {
   return channel_impl_->Send(message);
 }
 
-int Channel::GetClientFileDescriptor() const {
-  return channel_impl_->GetClientFileDescriptor();
-}
-
-int Channel::TakeClientFileDescriptor() {
-  return channel_impl_->TakeClientFileDescriptor();
-}
-
-bool Channel::AcceptsConnections() const {
-  return channel_impl_->AcceptsConnections();
-}
-
-bool Channel::HasAcceptedConnection() const {
-  return channel_impl_->HasAcceptedConnection();
-}
-
-bool Channel::GetClientEuid(uid_t* client_euid) const {
-  return channel_impl_->GetClientEuid(client_euid);
-}
-
-void Channel::ResetToAcceptingConnectionState() {
-  channel_impl_->ResetToAcceptingConnectionState();
-}
-
-base::ProcessId Channel::peer_pid() const { return 0; }
-
 // static
-bool Channel::IsNamedServerInitialized(const std::string& channel_id) {
-  return ChannelImpl::IsNamedServerInitialized(channel_id);
-}
-
-// static
 std::string Channel::GenerateVerifiedChannelID(const std::string& prefix) {
   // A random name is sufficient validation on posix systems, so we don't need
   // an additional shared secret.
   std::string id = prefix;
   if (!id.empty())
     id.append(".");
 
   return id.append(GenerateUniqueRandomChannelID());
 }
 
 }  // namespace IPC